The marine red alga Parviphycus felicinii sp. nov. (Gelidiellaceae, Gelidiales) is described from Italy. The species shows a predominantly creeping habit and forms small, dark purplish red turfs on smooth calcareous substrata at the supra-littoral level. It is distinguished by the following combination of features: size and shape of the outermost cortical cells in the upright thallus, number of tetrasporangia per tier, an extreme habitat. In culture, Parviphycus felicinii retains its creeping habit. In the presence of a suitable substratum, stolons are soon attached by rhizoids and growth is similar to that of field-collected plants. Tetrasporangial sori form in LD photo-regimes, in both floating and attached thalli. In the attached plants, sori only form at the upright apices, whilst in floating plants they form especially in lateral stichidium-like branchlets. Cultured tetraspores show high vitality and germination potential. The presumed gametophytes develop regularly, although they remain vegetative for six months in both SD and LD conditions.